337 nm matrix-assisted laser desorption/ionization of single aerosol particles

Matrix-assisted laser desorption/ionization (MALDI) mass spectra were obtai ned from single particles injected directly into a time-of-flight mass spec trometer, Aerosol particles were generated at atmospheric pressure using a piezoelectric single-particle generator or a pneumatic nebulizer and introd uced into the mass spectrometer through a series of narrow-bore tubes. Part icles were detected by light scattering that was used to trigger a 337 mn p ulsed nitrogen laser and the ions produced by laser desorption were mass se parated in a two-stage reflectron time-of-flight mass spectrometer, MALDI m ass spectra of single particles containing bradykinin, angiotensin II, gram icidin S, vitamin B-12 Or gramicidin D were obtained at mass resolutions gr eater than 400 FWHM, For the piezoelectric particle generator, the efficien cy of particle delivery was estimated to be similar to 0.02%, and 50 pmol o f sample were consumed for each mass spectrum. For the pneumatic nebulizer, mass spectra could be obtained from single particles containing less than 100 amol of analyte, although the sample consumption for a typical mass spe ctrum was over 400 pmol, Copyright (C) 1999 John Wiley & Sons, Ltd.